FERGUSON (CBS SF) — Jack Dorsey, co-founder of San Francisco-based Twitter and a native of St. Louis, has joined demonstrators protesting the police shooting of an unarmed black teenager in Ferguson, Missouri.

Dorsey, whose Twitter handle is “Jack,” has been tweeting short posts and Vine videos from the streets of Ferguson for the past two days.

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He announced his trip on Aug. 15 with this simple post:

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In later tweets, Dorsey said he was being joined by family members, including his parents, at the demonstrations.

Jack Dorsey Tweet

Jack Dorsey, co-founder of Twitter, tweeted that he was being joined by family at demonstrations in Ferguson.